Process of manufacturing pig iron



' UNITED ST TES I Patented Mar. 1, 1939 PATENT OFFICE 2,149,480 rno cnss or mime nemmz Max Paschke, Clansthal zellerfcid, and Eugen Peetz,

Duisburg-Huttenheim, Dusseldorf, Ger assignofs to ILA. Brasa'ert a Company,

- Chicago, 111., a corporation of Illinois a i No Drawing. Application October 1, 1937, Serial No. 166,718- lll Germany All! 15, 1936 are blown 'into the charge, which to a large ex This invention relates to a. new and improved process for the manufacture of pig iron low in sulphur and-more particularly to aprocessin which the desulphurization is carrlied out, in part at least, in the lower" portion of the blast. furnace.

Previously, processes for the manufacture of pig iron in the blast furnace, from a b en rich in particular in silica,,or sulphur, and ing coke' more or less high in sulphur, have been eveloped,

- in which fluxes, such as limestone, are dded to the burden only in such quantities that a' highsulphur iron is produced, together with an acid slag of low-melting point, the iron after tapping being des ulphurized by means of a basic slag, or other usual means. v According to this prior process the smelting of silicious low-grade ores, which is normally uneconomical, becomes possible in that desulphurization in the-blast furnace is dispensed with, and only sufficient limestone is added to the burden f to obtain'an .easily' fusible acid slag, for instance of the type obtained from a charcoal furnace. By

this means a large reduction in coke consumption is obtained when smelting low-grade silicious ores, because among other things, the'yield per unit of burden is considerably increased, and the fuel consumption in the blast furnace, when using easily fusible acid slags, is largely reduced, in comparison with operations using slags of the usual baslcit which, ho'wever, effect complete desulphuriza on'ofthe iron in the blast furnace.

It is an object of the present process to provide .a method for economically obtaining iron low in sulphur.

It is a further object to provide a method whereby a portion at least of the'sulphur is removed in the lower portion of a blast furnace.

It is also an object to provide a method whereby desulphurlzing reagents may be ,supplied directlyto the lower blast furnace zones- Other and further objects will appear as the description proceeds. i I

v In accordance with the present invention, prior processes are extendedand improved by carrying out some of the desulphurization in the lower part ofthe blast furnace, rather than entirely outside the furnace, without, however, sacrificing the advantages obtained. The burdening of the furnace is similar to that proposed in the above described process, i. e., the low-grade and silicious f iron'ores have only enough fluxes, such as limestone, added in order to form an easily fusible acid slag. In the lower part of the blast'furnace,

bosh, desulphurizlng agents preferably ,below the Iin its proximity,

'tent is reduced, or even melted. In'this way aconsiderable quantity of sulphur can be removed from the iron without having tov chargerthe desulphurizing coke. g Y g It is advantageous to blow in the desulphurizing agents, such as limestone, soda, fluorspar, manganese, in the form of ore, slag, Terra-manganese,

agents originally witl 'the" ore and and so forth, at such a position, low down in the blast furnace, that they will act as effectively as. a

possible directly on the pig-iron bath beneath the tuir res. In order to obtain the full advantages from smelting with a silicious andfr'ee-runn'ing slag, and to avoid blowing into the blast furnace morethan a minimum of the desulphurizlng agents, it

has proved advantageous to effect the blowing in of the desulphuri'zing agents intermittently.

This intermittent process is carried out according to one form as follows:

After a certain quantity of pig iron and acid slag has collected in the blast-furnace hearth,

. i. e., a short time before tapping, the free-running acid slag is removed from the high-sulphur iron. The desulphurizing agents arethen blown in on the practically slag-free pig iron, orpn the charge and after a short period the slag so formed iswithdrawn frbm the pig iron, or this" slag is tapped, together with the iron, in a known manner. The sulphur content of the pig iron, subjected in this way td a preliminary desulphurization, can if necessary be further reduced outside the blast furnace.

The blowing in of material to be smeltedis in itself known. a The present improvement of the prior processes makes possible the. smelting of highly silicious low-grade iron ores in the blast furnace to produce pig iron comparatively low in sulphur, retaining the advantages of the prior process, and obtaining economy of operation in that the cost of desulphurization outside of the blast furnace is saved. a

The-apparatus for blowing in the desulphurizing media, such as limestoneisoda, fiuorspar, manganese and so forth, are Mom, and do not require further description..

It will be understood that our improved process may be carried out with various forms of apparatus and may be modified to suit varying conditions and requirements and we contemplate such changes and-modifications as come within the spirit and scope. of the appended claims. We claim: Y 1. The process of manufacturing pig iron from a burden rich in silica and using sulphur con taining coke, characterized by the fact thatin the lower part of the furnace, de-sulphurizing agents are blown into the charge, which contains slagforming elements only in such quantities, that a high-sulphur iron would otherwise be produced together with-an acid slag of low melting point.

2. The process of manufacturing pig iron from a burden rich in silica and using sulphur containing coke, characterized by. the fact that in the lower part of the furnace, de-sulphurizing agents are blown into the charge, which contains slag-forming elements only in su h quantities, that a high-sulphur iron would therwise be produced together with an acid slag of low melting point, the pig iron being further desulphub ized after tapping by means of additional desul- .phurlzing reagenta 3.- The process of manufacturing pig iron from 2o a burden rich in silica and using sulphur containing coke. characterized by the fact that in the lower part of the furnace, demlphurizing agents are blown into the charge, which contains slagforming elements only in such quantities, that a high-sulphuriron would otherwise be produced together with an acid slag 01 low meltingpoiht,

the blowing-in oi the desulphurizing agents in the lower part of the blast furnace being effected intermittently after withdrawal of the tree-running siiicious slag from the pig iron.

4. The process of manuiacturing pig'iron from a burden rich in sulphur and using sulphur containing coke, characterized by the fact that in the lower part of the furnace, desulphurizing agents are blown into the charge. which contains slag-forming elements only in such quantities that a high-sulphur iron would otherwise be produced together with an acid slag of low melting point. a

' MAX PASCHKE.

EUGEN PEE'I'Z. 

